A conventional fractional-N PLL (phase-locked loop) has an input of reference frequency Fref and an output signal Fvco from the VCO (Voltage Control Oscillator). There are frequency regions (ranges) of the output signal Fvco in which spurs are very high when the VCO output frequency Fvco is close to the integer times of the input reference signal frequency Fref (so called the pitch frequency). Conventionally, a fractional-N PLL is usually not allowed to operate in these high spur frequency regions. Therefore, there is a need for a structure (and a method for operating the same) in which the fractional-N PLL can operate in any operating frequency region covering several pitch frequencies while keeping spurs low.